WO2001085811A2 - Copolymères pour photorésines et procédés afférents - Google Patents

Copolymères pour photorésines et procédés afférents Download PDF

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Publication number
WO2001085811A2
WO2001085811A2 PCT/US2001/014532 US0114532W WO0185811A2 WO 2001085811 A2 WO2001085811 A2 WO 2001085811A2 US 0114532 W US0114532 W US 0114532W WO 0185811 A2 WO0185811 A2 WO 0185811A2
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WIPO (PCT)
Prior art keywords
copolymer
photoresist
repeat unit
per micron
solvent
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PCT/US2001/014532
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English (en)
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WO2001085811A3 (fr
Inventor
Robert Clayton Wheland
Roger Harquail French
Frank Leonard Schadt Iii
Frederick C. Zumsteg, Jr.
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E.I. Du Pont De Nemours And Company
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Publication date
Application filed by E.I. Du Pont De Nemours And Company filed Critical E.I. Du Pont De Nemours And Company
Priority to US10/257,901 priority Critical patent/US6872503B2/en
Priority to DE60116484T priority patent/DE60116484T2/de
Priority to AU2001261205A priority patent/AU2001261205A1/en
Priority to JP2001582408A priority patent/JP2003532765A/ja
Priority to EP01935081A priority patent/EP1278786B1/fr
Publication of WO2001085811A2 publication Critical patent/WO2001085811A2/fr
Publication of WO2001085811A3 publication Critical patent/WO2001085811A3/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
    • C08F214/18—Monomers containing fluorine
    • C08F214/186—Monomers containing fluorine with non-fluorinated comonomers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/0046—Photosensitive materials with perfluoro compounds, e.g. for dry lithography
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/0048—Photosensitive materials characterised by the solvents or agents facilitating spreading, e.g. tensio-active agents
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/038—Macromolecular compounds which are rendered insoluble or differentially wettable
    • G03F7/0382—Macromolecular compounds which are rendered insoluble or differentially wettable the macromolecular compound being present in a chemically amplified negative photoresist composition
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
    • G03F7/0392—Macromolecular compounds which are photodegradable, e.g. positive electron resists the macromolecular compound being present in a chemically amplified positive photoresist composition

Definitions

  • the present invention pertains to a copolymer containing a first repeat unit derived from a fluoroolefin and a second repeat unit derived from an ethylenically unsaturated monomer containing an acid group or a protected acid group which cocopolymer is useful in a photoresist composition for imaging in the production of semiconductor devices.
  • the photoresist composition typically is applied to the silicon wafer by spin coating.
  • the silicon wafer may have various different material layers applied to it in other processing steps.
  • the silicon wafer may have a hard mask layer, typically of silicon dioxide or silicon nitride, applied below the photoresist composition layer.
  • an antireflective layer (ARC) may be applied below the photoresist composition layer, by a coating process (and is then typically referred to as a bottom anti-reflective (BARC)) or on top of the photoresist composition layer (and typically called a top-anti reflective layer (TARC)).
  • BARC bottom anti-reflective
  • TARC top-anti reflective layer
  • the thickness of the resist layer is sufficient to resist the dry chemical etch processes used in transferring a pattern to the silicon wafer.
  • the photoresist composition generally comprises a film forming copolymer which may be photoactive and a photosensitive composition that contains one or more photoactive components.
  • a film forming copolymer which may be photoactive
  • a photosensitive composition that contains one or more photoactive components.
  • the photoactive component upon exposure to electromagnetic radiation (e.g., UV light), the photoactive component acts to change the rheological state, solubility, surface characteristics, refractive index, color, electromagnetic characteristics or other such physical or chemical characteristics of the photoresist composition.
  • Lithography in the UV at 365 nm is a currently established image-forming process for making semiconductor devices. The features formed by this process have a resolution limit of about 0.35-0.30 micron.
  • Known photoresist compositions for lithography using a 365 nm wavelength are made from novolak copolymers and diazonaphthoquinones as dissolution inhibitors.
  • Lithography in the deep UV at 248 nm has been found to have a resolution limit of approximately
  • the known photoresist compositions for this process are made from p-hydroxystyrene copolymers. Lithographic processes using electromagnetic radiation at even shorter wavelengths are looked to for forming very fine features because the use of lower wavelengths correspond to higher resolution; that is, in deep (wavelength less than 300 nm), vacuum (wavelength less than 200 nm) or even the extreme (wavelength less than 30 nm) ultraviolet. However, at wavelengths of 193 nm or shorter, the photoresist compositions known for use at 3 5 nm and 248 nm have been found to lack sufficient transparency.
  • the transparency requirements for photoresist compositions are usually on the order of allowing about 20 to about 40% of incident light to penetrate the full thickness of the resist layer to produce an image with well-defined, vertical side walls, which are important in achieving high resolution and minimizing defects.
  • Copolymers which lack transparency absorb too much light and thereby produce an unacceptable image with low resolution and too many defects.
  • a thick film layer of the photoresist material is beneficial for high resolution and low defects.
  • thick films tend to lack transparency at low wavelengths.
  • T the light transmission
  • the film thickness in angstroms (t) and the optical absorbance per micron (of film thickness) of a film layer containing the copolymer was calculated as a function of the film thickness in angstroms (t) and the optical absorbance per micron (of film thickness) of a film layer containing the copolymer. The results are shown for a copolymeric resist for use at 157 nm in Figure 1 and for a copolymeric resist for use at 193 nm in Figure 2.
  • an index of refraction (n) for the resist of 1.6 is used and no effect(s) of the underlying silicon substrate, representing the light transmitted tlirough an unsupported copolymer film layer have been considered to represent the light transmitted through an unsupported film.
  • n index of refraction
  • the molecular weight of a polymer for a photoresist composition which is sufficient for high film-forming properties may be detrimental to transparency at low wavelengths.
  • Table 1 shows the known absorption maxima for simple hydrocarbon H(CH2) n H and fluorocarbon F(CF2) n F chains. As these chains become longer, their absorption moves to longer wavelengths, first starting up at 157 nm for hydrocarbons when n is greater than 1 and for fluorocarbons when n is greater than about 10. This implies that polymers having (CH 2 ) n chain segments with n greater than 1 and (CF 2 ) n segments with n greater than about 10 are likely to be highly absorbing at 157 nm.
  • These three copolymers are TeflonTM AF having an absorbance per micron of about 0.5 ⁇ m" 1 , poly(methysiloxane) having an absorbance per micron of about 1.5 ⁇ m" 1 , and poly(phenylsiloxane) having an absorbance per micron of about 2.5 ⁇ m" 1 .
  • Attempts to convert these pure copolymers into thin films both sensitive to light and capable of aqueous base development have tended to increase absorption at 157 nm. Indeed, none of the three transparent copolymer systems found by Bloomstein have yet been successfully converted into practical resists. There is a need for photosensitive, aqueous base developable copolymers sufficiently transparent to UV light to make a good resist. Resists effective at 157 nm should also work at longer wavelengths (for example, 193 and 248 nm).
  • photolithography at the shorter wavelengths would provide the very fine features having lower resolution limits; that is, a resolution limit of approximately 0.18-0.12 micron at 193 nm, approximately 0.07 micron at 157 mn photoresist compositions that will be sufficiently transparent at these short wavelenths are needed.
  • Figure 1 is a plot of the % transmission (T) at 157 nm of resist films with optical absorbance per micron at 157 nm in units of inverse microns of 1/ ⁇ m to 6/ ⁇ m versus the resist film thickness (t) in angstroms. Transmission was calculated for air underlying the resist film so as to neglect the underlying semiconductor wafer.
  • Figure 2 is a plot of the % transmission (T) at 193 nm of resist films with optical absorbance per micron at 193 nm in units of inverse microns of 1/ ⁇ m to 2/ ⁇ m versus the resist film thickness (t) in angstroms. Transmission was calculated for air underlying the resist film so as to neglect the underlying semiconductor wafer.
  • Figure 3 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/NF/tBA) (copolymer of Example 1) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 4 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/VF/tBA) (copolymer of Example 2) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 5 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/NF2/tBA) (copolymer of Example 3) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 6 describes the optical absorbance per micron in units of inverse microns for P(HFIB/NF2/tBA) (copolymer of Example 4) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 7 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB NAc/tBA) (copolymer of Example 5) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 8 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/NF2/tBA) (copolymer of Example 7) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 9 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/NF2/tBMA) (copolymer of Example 8) and a formulated photoresist (8B of Example 8) of P(HFIB:VF2:tBMA) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 10 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/VF2/tBMA) (copolymer of Example 9) and two formulated photoresists (9 A and 9B of Example 9) of P(HFIB:VF2:tBMA) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • Figure 11 is a plot of the optical absorbance per micron in units of inverse microns for P(HFIB/tBA) (copolymer of Example 10) and a formulated photoresist (10B of Example 10) of P(HFIB/tBMA) versus wavelength lambda ( ⁇ ) in units of nanometers.
  • the invention is a copolymer comprising:
  • Rj and R are independently selected from the group consisting of C1-C3 perfluoroalkyl, or taken together are (CF2) n wherein n is 3 to 5;
  • the invention is directed to a photoresist comprising the copolymer and at least one photoactive component. In yet another embodiment, the invention is directed to a process for preparing a photoresist image on a substrate comprising
  • the copolymer comprising a first repeat unit derived from a fluoroolefin and a second repeat unit derived from (meth)acrylate ester-containing copolymer present as a component in a photoresist preferably has an optical absorbance per micron of less than 5.0 ⁇ m" 1 at a wavelength of 157 nm.
  • the copolymer comprising a first repeat unit derived from a fluoroolefin and a second repeat unit derived from (meth)acrylate ester-containing copolymer can be further comprised of an aliphatic polycyclic functionality.
  • the photoactive component can be a photoacid generator.
  • the photoresists can be further comprised of a dissolution inhibitor.
  • a key characteristic of the copolymers (and photoresists comprised of the copolymers) of this invention is the cooperative combination in the copolymer of the first repeat unit with the second repeat unit. Another characteristic of the copolymer is that it does not detrimentally absorb in the vacuum and far UV. The minimization of functionality, such as aromatic groups, which absorb in the ultraviolet in the repeat units of the copolymer is desirable in order for the copolymer to possess suitable, preferably high, optical transparency.
  • the first repeat unit is derived from a fluoroolefin having the structure:
  • Rj and R 2 are independently selected from the group consisting of C1-C3 perfluoroalkyl, or taken together are (CF 2 ) n wherein n is 3 to 5.
  • Suitable examples of specific comonomers include, but are not limited to, hexafluoroisobutylene and decafluoroisohexylene.
  • the second repeat unit is derived from a first ethylenically unsaturated comonomer comprising an acid group or a protected acid group.
  • a first ethylenically unsaturated comonomer comprising an acid group or a protected acid group.
  • Suitable, but non-limiting examples of an acid group or a protected acid group for this invention are described below in the section entitled "Protective Groups for Removal by PAC Catalysis".
  • Suitable, non-limiting examples of second ethylenically unsaturated comonomers are vinyl fluoride, vinylidene fluoride, vinyl acetate, trifluoroethylene, chlorotrifluoroethylene, tetrafluoroethylene, 4,5-difluoro-2,2- bis(trifluoromethyl)-l,3-dioxole (perfluorodimethyldioxole), 2,2- bis(trifluoromethyl)-l,3-dioxole (dihydroperfluoromethyldioxole), vinyl alcohol (i.e., a vinyl acetate unit hydrolyzed after copolymerization), l,3-dioxole-2-one (vinylene carbonate), and maleic anhydride.
  • vinyl fluoride vinylidene fluoride
  • vinyl acetate trifluoroethylene
  • chlorotrifluoroethylene tetrafluoroethylene
  • 4,5-difluoro-2
  • the copolymers of this invention preferably are characterized by a repeat unit derived from at least one first ethylenically unsaturated comonomer containing an acid group or a protected acid group (e.g., a t-alkyl ester group) that is present in these copolymers from about 25 to about 60 mole percent and a repeat unit derived from at least one or more fluoroolefin(s) that are present in the copolymer from about 40 to about 65 mole percent.
  • the fluoroolefin t-alkyl ester copolymers more preferably with respect to achieving low optical absorbance per micron are characterized by a repeat unit derived from at least one first ethylenically unsaturated comonomer containing protected t-alkyl ester group that is present in the copolymers at less than or equal to 60 mole percent, and, still more preferably, at less than or equal to 50 mole percent.
  • a repeat unit derived from at least one first ethylenically unsaturated comonomer containing protected t-alkyl ester group that is present in the copolymers at less than or equal to 60 mole percent, and, still more preferably, at less than or equal to 50 mole percent.
  • alternating short (CH 2 ) n and (CF ) m segments in the polymer will be likely to provide a relatively transparent polymer.
  • monomers such as vinylidene fluoride in which CF alternates with CH and hexafluoroisobutylene in which C(CF3) 2 alternates with CH 2 favor transparency at 157 nm.
  • n and m, and the ratio of hydrocarbon to fluorocarbon in the polymer chain can be varied depending upon the other components of the photoresist and the other repeat units of the polymer, as one skilled in the art would be able to determine, in general more than two immediately adjacent CH2 groups (i.e.
  • the appropriate alternating sequence can be in the monomer from which the polymer is derived. Alternatively, the alternating sequence can be achieved during the polymerization process by techniques Icnown in the art.
  • the copolymers of this invention optionally may be further comprised of a repeat unit derived from a compound comprising an aliphatic polycyclic group.
  • Aliphatic polycyclic groups are of interest because they can often beneficially increase plasma etch resistance or raise T g by stiffening a polymer chain. They can be incorporated in the polymer as part of the chain (as in the case of norbornene copolymers) or as pendant side groups (as in the case of adamantyl acrylate copolymers).
  • a suitable aliphatic polycyclic group can contain from about seven to about eighteen carbon atoms, can contain olefinic unsaturation, and one or more of the ring carbons can be replaced by heteratoms such as oxygen, nitrogen, and sulfur.
  • the aliphatic polycyclic group is a fused polycyclic hydrocarbon containing from about seven to about twelve carbon atoms with two to four rings.
  • the aliphatic polycyclic group can be substituted or unsubstituted. Ifthe aliphatic polycyclic group is substituted, the substituent group can contain from one to about four carbon atoms and, optionally, heteroatoms such as oxygen, nitrogen, sulfur, or halogen such as chlorine or fluorine.
  • Particularly desirable functional groups are those such as -OH or - C(CF3) 2 OCH 2 OCH3 which aid in wetting, aqueous solubility, and/or photodevelopment while adding relatively little to light absorption.
  • the percentage of repeat units of the copolymer containing the aliphatic polycyclic group ranges from about 5 to about 60 mole percent; and preferably from about 10 to about 50 mole percent.
  • the fluoroolefin copolymers of this invention can contain additional functional groups beyond those specifically mentioned herein with the proviso that, preferably, the copolymer is substantially free of aromatic groups and still more preferably aromatic groups are absent in these copolymers.
  • the presence of aromatic groups in these copolymers has been found to detract from their transparency and result in their being too strongly absorbing in the near, deep and vacuum UV regions of the electromagnetic spectrum to be suitable for use in photoresists that are imaged at wavelengths in the UV. For this reason, in one embodiment of the invention, the copolymer is free of aromatic groups.
  • the copolymer has an optical absorbance per micron of less than 5.0 ⁇ r 1 at a wavelength of 157 nm, preferably less than 4.0 ⁇ m" 1 at this wavelength, more preferably, less than 3.5 ⁇ m _1 at this wavelength, and, most preferably, less than 3.0 ⁇ nr 1 at this wavelength.
  • Copolymerizations can be carried out by any of the common methods known to those skilled in the art including solution, dispersion, or emulsion copolymerizations employing either batch or continuous processes with either an initial single charge, intermittant, or a continuous feed of reactants.
  • the copolymerizations were most conveniently run using a single initial charge of monomers, organic solvent, and initiator to an autoclave.
  • the contents of the autoclave were then typically agitated under pressure usually about 10 to about 500 psi (about 0.70 to about 35.15 kg/cm 2 ), typically about 20 to about 100 psi (about 1.41 to about 7.03 kg/cm 2 ) for about 1 to about 48 hours, typically about 6 to about 18 hours at about 10 to about 100°C, typically about 20 to about 75°C, the temperature and reaction time being chosen to match the half-life of the initiator and the thermal stability of the protected acid groups in the copolymer.
  • Common free radical intiators can be used and include diacyl peroxides such as DP
  • HFPO dimer peroxide percarbonates such as Perkadox(TM) 16N [di(4-t- butylcyclohexyl)peroxydicarbonate), and AIBN (2,2'-azobisisobutyronitrile).
  • Perkadox(TM) 16N di(4-t- butylcyclohexyl)peroxydicarbonate
  • AIBN 2,2'-azobisisobutyronitrile
  • Organic fluids that do not significantly interfere with radical copolymerization such as fluorocarbons, chlorofluorocarbons, chlorofluorohydrocarbons, and hydrofluorocarbons are desirable solvents for the copolymerization.
  • interfere with copolymerization we mean solvents that change molecular weight by chain transfer or that terminate copolymerization by reaction with the growing radical ends.
  • Preferred solvents include Vertrel(TM) XF (CF 3 CFHCFHCF 2 CF 3 ) and Freon(TM) 113 (CF 2 C1CC1 2 F).
  • the photoresists of this invention are comprised of a copolymer (as described supra) and at least one photoactive component (PAC, discussed infra).
  • the photoresists can either be positive-working or negative-working. Positive- working photoresists are preferred.
  • These photoresists can optionally comprise dissolution inhibitors and/or other additional components. Examples of additional components which can be added include, but are not limited to, resolution enhancers, adhesion promoters, residue reducers, coating aids, plasticizers, and T g (glass transition temperature) modifiers.
  • a typical photoresist formulation comprises the copolymer, as described herein, comprising the first repeat unit and the second repeat unit, solvent and a photoactive component which are usually combined and mixed together, typically, at ambient temperature.
  • a photoactive component which are usually combined and mixed together, typically, at ambient temperature.
  • Illustrative, nonlimiting solvents which may be used include cyclohexanone, 2-heptanone, l,2-bis(l,l,2,2-tetrafluoroethoxy)ethane (HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H), or mixtures of two or more of the foregoing solvents.
  • a cosolvent which facilitates the film forming capabilities of a photoresist formulation containing the copolymer of this invention can be used.
  • a fluorinated compound, 1 ,2-bis( 1 , 1 ,2,2- tetrafluoroethoxy)ethane having the structure HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H is a suitable cosolvent.
  • compositions of this invention contain at least one photoactive component (PAC) that usually is a compound that affords either acid or base upon exposure to actinic radiation. If an acid is produced upon exposure to actinic radiation, the PAC is termed a photoacid generator (PAG). If a base is produced upon exposure to actinic radiation, the PAC is termed a photobase generator (PBG).
  • Suitable photoacid generators for this invention include, but are not limited to, 1) sulfonium salts (structure I), 2) iodonium salts (structure II), and 3) hydroxamic acid esters, such as structure III.
  • R4-R6 are independently substituted or unsubstituted aryl or substituted or unsubstituted C C 2 o alkylaryl (aralkyl).
  • Representative aryl groups include, but are not limited to, phenyl and naphthyl.
  • Suitable substituents include, but are not limited to, hydroxyl (-OH) and C ⁇ -C 2 o alkyloxy (e.g., C ⁇ oH 2 O).
  • Protective Groups for Removal by PAC Catalysis A copolymer of this invention contains, in the second repeat unit, and, optionally, in one or more other repeat unit(s), one or more acid groups or protected acid groups (e.g., protected carboxylic acid groups or protected fluoroalcohol groups) that can yield, by catalysis of acids generated photolytically from photoactive compounds (PACs), hydrophilic acid groups which enable development of resist coatings.
  • PACs photoactive compounds
  • a protected acid group is an acid group that is protected with a protecting group.
  • a given protected acid group is one that is normally chosen on the basis of its being acid labile, such that when photoacid is produced upon imagewise exposure, the acid will catalyze deprotection and production of hydrophilic acid groups that are at this point unprotected and which are necessary for development under aqueous conditions.
  • copolymers may also contain one or more acid groups that are not protected. The copolymers may contain none, some, or all acid groups that is/are protected.
  • Photoresists comprised of the copolymers of this invention can be heated to promote deprotection necessary for image formation. An acid group when deprotected affords free acid that enhances the solubility, swellability, and/or dispersibility in aqueous environments of the copolymer to which the acid group is bonded.
  • Nonlimiting examples of components having protected acid groups that yield an acid group as the hydrophilic group upon exposure to photogenerated acid include A) esters capable of forming, or rearranging to, a tertiary cation, B) esters of lactone, C) acetal esters, D) ⁇ -cyclic ketone esters, E) ⁇ -cyclic ether esters, F) MEEMA (methoxy ethoxy ethyl methacrylate) and other esters which are easily hydrolyzable because of anchimeric assistance, G) carbonates formed from a fluorinated alcohol and a tertiary aliphatic alcohol.
  • category A Some specific examples in category A) are t-butyl ester, t-amyl ester, 2-methyl-2-adamantyl ester, and isobornyl ester.
  • category B Some specific examples in category B) are ⁇ -butyrolactone-3-yl, ⁇ -butyrolactone-2-yl, mavalonic lactone, 3-methyl- ⁇ - butyrolactone-3-yl, 3-tetrahydrofuranyl, and 3-oxocyclohexyl.
  • category C Some specific examples in category C) are 2-tetrahydropyranyl, 2-tetrahydrofuranyl, and
  • 2,3-propylenecarbonate-l-yl examples include various esters from addition of vinyl ethers, such as, for example, ethoxy ethyl vinyl ether, methoxy ethoxy ethyl vinyl ether, and acetoxy ethoxy ethyl vinyl ether.
  • components having protected acid groups that yield an acid as the hydrophilic group upon exposure to photogenerated acid or base include, but are not limited to, t-butoxycarbonyl (t-BOC), t-butyl ether, and 3-cyclohexenyl ether.
  • the acid group or protected acid group may also be derived from a fluoroalcohol or fluoroether.
  • One or more of the first repeat unit, the second repeat unit, the third repeat unit or another component may be derived from at least one ethylenically unsaturated compound containing a fluoroalcohol or fluoroether group having the structure:
  • Rf and R_' are the same or different fluoroalkyl groups of from 1 to about 10 carbon atoms or taken together are (CF 2 ) n wherein n is 2 to 10, and R x is a hydrogen atom or a C3-C6 -secondary- or tertiary-alkyl group.
  • a tertiary-alkyl group is preferred.
  • the second repeat unit can be derived from any one or more of the foregoing acid groups or protected acid groups or the second repeat unit can be derived from a tertiary-alkyl acrylates or tertiary-alkyl methacrylates, wherein the alkyl group contains from four to about ten carbon atoms. Tertiary-alkyl acrylates are more preferred.
  • the most preferred monomer comprised of a protected acid group is tertiary-butyl acrylate (tBA).
  • the components having protected acid groups are repeat units having protected acid groups that have been incorporated in the base copolymer.
  • the protected acid groups are present in one or more monomer(s) that are copolymerized to form a given copolymer of this invention.
  • a copolymer can be formed by copolymerization with an acid-containing monomer and then subsequently the acid group can be partially or wholly converted by appropriate means to derivatives having protected acid groups.
  • a copolymer of HFIB/tBA/NF2 (copolymer containing hexafluoroisobutylene, t- butyl acrylate, and vinylidene fluoride) is a copolymer within the scope of the invention having t-butyl ester groups as protected-acid groups.
  • dissolution inhibitors can be utilized in this invention.
  • DIs dissolution inhibitors
  • 157 or 193 nm resists should be designed/chosen to satisfy multiple needs including dissolution inhibition, plasma etch resistance, and adhesion behavior of resist compositions comprising a given DI additive.
  • Some dissolution inhibiting compounds also serve as plasticizers in resist compositions.
  • Bile-salt esters are particularly useful as DIs in the compositions of this invention.
  • Bile-salt esters are known to be effective dissolution inhibitors for deep UV resists, beginning with work by Reichmanis et al. in 1983. (E. Reichmanis et al., "The Effect of Substituents on the Photosensitivity of 2-Nitrobenzyl Ester Deep UV Resists", J Electrochem. Soc.
  • Bile-salt esters are particularly attractive choices as DIs for several reasons, including their availability from natural sources, their possessing a high alicyclic carbon content, and particularly for their being transparent in the Deep and vacuum UV region of the electromagnetic spectrum (e.g., typically they are highly transparent at 193 nm). Furthermore, the bile-salt esters are also attractive DI choices since they may be designed to have widely ranging hydrophobic to hydrophilic compatibilities depending upon hydroxyl substitution and functionalization.
  • Representative bile-acids and bile-acid derivatives that are suitable as additives and/or dissolution inhibitors for this invention include, but are not limited to, those illustrated below, which are as follows: cholic acid (IV), deoxycholic acid (V), lithocholic acid (VI), t-butyl deoxycholate (VII), t-butyl lithocholate (VIII), and t-butyl-3- ⁇ -acetyl lithocholate (IX).
  • Bile-acid esters, including compounds VII-IX, are preferred dissolution inhibitors in this invention.
  • Negative- Working Photoresists Some embodiments of this invention are negative-working photoresists. These negative-working photoresists comprise at least one binder copolymer comprised of acid-labile groups and at least one photoactive component that affords photogenerated acid. Imagewise exposure of the resist affords photogenerated acid which converts the acid-labile groups to polar groups (e.g., conversion of ester group (less polar) to acid group (more polar)). Development is then done in an organic solvent or critical fluid (having moderate to low polarity), which results in a negative-working system in which exposed areas remain and unexposed areas are removed.
  • polar groups e.g., conversion of ester group (less polar) to acid group (more polar)
  • crosslinking agents can be employed as required or optional photoactive component(s) in the negative- working compositions of this invention.
  • a crosslinking agent is required in embodiments that involve insolubilization in developer solution as a result of crosslinking, but is optional in preferred embodiments that involve insolubilization in developer solution as a result of polar groups being formed in exposed areas that are insoluble in organic solvents and critical fluids having moderate/low polarity).
  • compositions of this invention can contain optional additional components.
  • additional components include, but are not limited to, resolution enhancers, adhesion promoters, residue reducers, coating aids, surfactants, plasticizers, and T g (glass transition temperature) modifiers.
  • the photoresist compositions of this invention are sensitive in the ultraviolet region of the electromagnetic spectrum and especially to those wavelengths ⁇ 365 nm.
  • Imagewise exposure of the resist compositions of this invention can be done at many different UV wavelengths including, but not limited to, 365 nm, 248 nm, 193 nm, 157 nm, and lower wavelengths.
  • Imagewise exposure is preferably done with ultraviolet light of 248 nm, 193 nm, 157 nm, or lower wavelengths, more preferably it is done with ultraviolet light of 193 nm, 157 nm, or lower wavelengths, and most preferably, it is done with ultraviolet light of 157 nm or lower wavelengths.
  • Imagewise exposure can either be done digitally with a laser or equivalent device or non-digitally with use of a photomask.
  • Suitable laser devices for imaging of the compositions of this invention include, but are not limited to, an argon-fluorine excimer laser with UV output at 193 nm, a krypton-fluorine excimer laser with UV output at 248 nm, and a fluorine (F2) laser with output at 157 nm.
  • F2 laser fluorine
  • the copolymers of this invention can be formulated as a positive resist wherein the areas exposed to UN light become sufficiently acidic to be selectively washed out with aqueous base. Sufficient acidity is imparted to the copolymers by acid or protected acid (which can be 100% in protected form prior to exposure provided deprotection occurs during exposure to afford sufficient free acid to provide for development) such that aqueous development is possible using a basic developer such as sodium hydroxide solution, potassium hydroxide solution, or tetramethylammonium hydroxide solution.
  • a basic developer such as sodium hydroxide solution, potassium hydroxide solution, or tetramethylammonium hydroxide solution.
  • a given copolymer for aqueous processability (aqueous development) in use is typically a carboxylic acid-containing and/or fluoroalcohol-containing copolymer (after exposure) containing at least one free carboxylic acid group and/or fluoroalcohol group.
  • the level of acid groups e.g., free carboxylic acid or fluoroalcohol groups
  • the copolymer of the photoresist When an aqueous processable photoresist is coated or otherwise applied to a substrate and imagewise exposed to UN light, the copolymer of the photoresist must have sufficient protected acid groups and/or unprotected acid groups so that when exposed to UN the exposed photoresist will become developable in basic solution.
  • the photoresist layer will be removed during development in portions which are exposed to UN radiation but will be substantially unaffected in unexposed portions during development by aqueous alkaline liquids such as wholly aqueous solutions containing 0.262 ⁇ tetramethylammonium hydroxide (with development at 25°C usually for less than or equal to 120 seconds) or 1%> sodium carbonate by weight (with development at a temperature of 30°C usually for less than 2 or equal to 2 minutes).
  • aqueous alkaline liquids such as wholly aqueous solutions containing 0.262 ⁇ tetramethylammonium hydroxide (with development at 25°C usually for less than or equal to 120 seconds) or 1%> sodium carbonate by weight (with development at a temperature of 30°C usually for less than 2 or equal to 2 minutes).
  • aqueous alkaline liquids such as wholly aqueous solutions containing 0.262 ⁇ tetramethylammonium hydroxide (with development at 25°C usually for less than or
  • a critical fluid is one or more substances heated to a temperature near or above its critical temperature and compressed to a pressure near or above its critical pressure.
  • Critical fluids in this invention are at least at a temperature that is higher than 15°C below the critical temperature of the fluid and are at least at a pressure higher than 5 atmospheres below the critical pressure of the fluid.
  • Carbon dioxide may be used for the critical fluid in the present invention.
  • Various organic solvents can also be used as developer in this invention. These include, but are not limited to, halogenated solvents and non- halogenated solvents. Halogenated solvents are preferred and fluorinated solvents are more preferred.
  • Transmittance Transmittance, T, ratio of the radiant power transmitted by a sample to the radiant power incident on the sample and is measured for a specified wavelength ⁇ (e.g., nm).
  • HFIB Hexafluoroisobutylene 2-trifluoromethyl-3 ,3 ,3 -trifluoro- 1 -propene
  • Vazo® 67 2,2 ' - Azobis(2-methyl butyronitrile) E. I. du Pont de Nemours and Company, Wilmington, DE
  • VertrelTM XF CF 3 CFHCFHCF 2 CF 3
  • Ultraviolet UV Ultraviolet region of the electromagnetic spectrum which ranges from 10 nanometers to 390 nanometers Extreme UV (EUV) Region of the electromagnetic spectrum in the ultraviolet that ranges from 10 nanometers to UV.
  • EUV Extreme UV
  • VUV Vacuum UV Region of the electromagnetic spectrum in the ultraviolet that ranges from 30 nanometers to
  • Deep UV Region of the electromagnetic spectrum in the ultraviolet that ranges from 200 nanometers to
  • copolymer compositions were estimated by carbon/hydrogen analysis in which case compositions were believed accurate within 10 to 15 mole percent.
  • copolymer compositions were occasionally determined by Carbon- 13 NMR in which case compositions were believed accurate within 5 to 10 mole percent.
  • the optical absorbance per micron of a film containing the copolymer of this invention was determined by forming a film of the copolymer onto a substrate. This was accomplished by the standard procedure of spin coating a solution of the copolymer of this invention onto a CaF 2 substrate and followed by drying the coated substrate. The optical absorbance was measured per micron of film thickness. The VUV transmission of each CaF 2 substrate was measured prior to coating of the substrate. Then the VUV transmission of the coated substrate was measured, and using the measured film thickness, the optical absorbance per micron for the film, as a function of wavelength, was determined, which included the values of the optical absorbance per micron for wavelengths of 157 nm and 193 nm.
  • VUV transmission of the CaF 2 substrates and the films on the CaF 2 substrates were measured with a VUV Spectrophotometer using a laser plasma light source, a sample chamber capable of both transmission and reflectance measurements, a 1 meter monochromator and a sodium salicylate phosphor coated 1024 element photodiode detector. This procedure is discussed in greater detail in R. H. French, "Laser-Plasma Sourced, Temperature Dependent VUV
  • VUV transmission of the CaF 2 substrates and the copolymer films on the CaF 2 substrates for Examples 8, 9 and 10 were measured with a VUV Ellipsometer capable of transmission and reflectance measurements.
  • This VUV Ellipsometer uses a deuterium and Xenon lamp light sources, a double monochromator, an AutoRetarder for greater accuracy and a photomultiplier and a photodiode detector.
  • Samples were first spin-coated on silicon wafers on a Brewer Cee (Rolla, MO), Spincoater/Hotplate model 100CB. a) Two to four silicon wafers were spun at different speeds (e.g., 2000, 3000, 4000, 6000 rpm) to obtain differing film thicl ⁇ iess and the coated wafers were subsequently baked at 80°C for 2 min.
  • the dried films were then measured for thickness on a Filmetrics F20 Film Measurement System (Filmetrics, Inc., 7675 Dagget St., Suite 140, San Diego, CA 92111-2255) or on a Dektak Stylus Profiler Model IIA, (Veeco Metrology Group, 112 Robin Hill Road, Santa Barbara, CA 93117). Spin speeds were then selected from this data to spin the CaF 2 substrates for the spectrometer measurement. b) CaF 2 substrates (1/2" dia. x 0.040" thick) were selected and the transmission of the substrate determined on the VUV Spectrophotometer or the VUV Ellipsometer.
  • the optical absorbance per micron which is the absorbance A per micron of film thickness
  • Equation 1 The optical absorbance per micron, which is the absorbance A per micron of film thickness
  • A/ ⁇ mfii m is the optical absorbance per micron in units of ⁇ m _1 of a given film determined for a specified wavelength of light.
  • Afilm i s me absorbance (unitless) of a given film determined for a specified wavelength of light.
  • ⁇ substrate s tne transmittance (unitless) of a substrate e.g. a calcium fluoride plate
  • a substrate e.g. a calcium fluoride plate
  • Tsam p le is the transmittance (unitless) of a sample of a given film and a substrate determined for a specified wavelength of light.
  • tf j i is thickness of a given film in microns.
  • the optical absorbance per micron A/ ⁇ m has units of inverse microns (or 1 /micron, where a micron, is a micrometer or ⁇ m of film thickness).
  • the absorbance/micron of films were measured for films spun coated on to CaF2 substrates using the above-described methods.
  • the VUV transmission of each CaF 2 substrate was measured prior to the spin coating of the film.
  • the VUV transmission of the film on that particular CaF substrate was measured, and using the measured film thickness (reported in Table 1) and equation 1, the values of the absorbance/micron for the copolymers, as a function of wavelength were determined, and the values of the absorbance/micron for wavelengths of 157 nm and 193 nm are tabulated in Table 2.
  • the term "clearing dose” indicates the minimum exposure energy density (e.g., in units of mJ/cm 2 ) to enable a given photoresist film, following exposure, to undergo development.
  • a 210 ml stainless steel autoclave was loaded with 15 ml CF2C1CC12F and 14 ml of t-butylacrylate (tBA). After chilling to less than -20°C, 20 ml of about 0.18 M DP in VertrelTM XF were added. The autoclave was sealed, chilled, evacuated, and 64 g of hexafluoroisobutylene (HFIB) and 4 g of vinyl fluoride (VF) added. The reaction mixture was shaken overnight (about 21 hours) at ambient temperature, reaching a peak of 34.9 psi (241 kPa) at 22.2°C. The fluid reaction mixture was evaporated to dryness, put under pump vacuum for a week, and then dried in a 65-90°C vacuum oven for 7 hours. This gave 14 g of brittle solid, which was characterized below.
  • HFIB hexafluoroisobutylene
  • VF vinyl fluoride
  • optical absorbance per micron in units of inverse microns for P(HFIB/NF/tBA) versus wavelength lambda ( ⁇ ) in units of nanometers is shown in Figure 3.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 2.89/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.01/micron.
  • a thin film was prepared for lithographic evaluation by spin coating the above formulation on a 4 inch (10.2 cm) diameter Type "P", ⁇ 100> orientation, silicon wafer. Spin coating was done using a Brewer Science Inc. Model- 100CB combination spin coater/hotplate. Development was performed on a Litho Tech Japan Co. Resist Development Analyzer (Model-790).
  • the wafer was prepared by depositing 6 ml of hexamethyldisilazane (HMDS) primer and spinning at 1000 rpm for 5 sec. and then 3500 rpm for 10 sec. Then 6 ml of the above solution, after filtering through a 0.45 ⁇ m PTFE syringe filter, was deposited and spun at 3000 rpm for 60 seconds and baked at 120°C for 60 seconds.
  • HMDS hexamethyldisilazane
  • 248 nm imaging was accomplished by exposing the coated wafer to light obtained by passing broadband UV light from an ORIEL Model-82421 Solar Simulator (1000 watt) through a 248 nm interference filter which passes about 30% of the energy at 248 nm. Exposure time was 30 seconds, providing an unattenuated dose of 20.5 mJ/cm2. By using a mask with 18 positions of varying neutral optical density, a wide variety of exposure doses were generated. After exposure, the exposed wafer was baked at 120°C for 120 seconds. The wafer was developed in aqueous tetramethylammonium hydroxide (TMAH) solution (ONKA NMD-3, 2.38% TMAH solution). Development time was 60 sec. A positive image was produced on the wafer with a clearing dose of approximately 21 mJ/cm 2 . EXAMPLE 2
  • TMAH tetramethylammonium hydroxide
  • a 210 ml stainless steel autoclave was loaded with 15 ml CF 2 C1CC1 2 F and 14 ml of t-butylacrylate (tBA). After chilling to less than -20°C, 20 ml of about 0.16 M DP in NertrelTM XF were added. The autoclave was sealed, chilled, evacuated, and 32 g of hexafluoroisobutylene and 5 g of vinyl fluoride added. The reaction mixture was shaken overnight (about 12 hours) at ambient temperature, reaching a peak of 207 psi (1430 kPa) at 24.8°C. The fluid reaction mixture was evaporated to dryness, put under pump vacuum for 18 hours, and then dried in 75°C vacuum oven for 30 hours. This gave 17 g of brittle solid, which was characterized below.
  • Tg glass transition temperature
  • optical absorbance per micron in units of inverse microns for P(HFIB/VF/tBA) (0.22/0.39/0.39) versus wavelength lambda ( ⁇ ) in units of nanometers is shown in Figure 4.
  • the optical absorbance per micron at 157 nm determined from the film is 3.64/micron.
  • the optical absorbance per micron at 193 nm determined from the film is 0.08/micron.
  • the reaction mixture was shaken overnight (about 20 hours) at ambient temperature, reaching a peak of 79 psi (540 kPa) at 20.6°C.
  • the fluid reaction mixture was evaporated to dryness, put under pump vacuum for a week, and dried for 7 hours in a 65-90°C vacuum oven. This gave 13 g of brittle solid, which was characterized as given below.
  • HFIB NF2/tBA copolymer (0.25/0.2/0.55) as described in this example. 0.234
  • a 210 ml stainless steel autoclave was loaded with 15 ml VertrelTM XF and 5 ml of t-butylacrylate (tBA). After chilling to less than -20°C, 20 ml of about 0.18 M DP in VertrelTM XF were added. The autoclave was sealed, chilled, evacuated, and 32 g of hexafluoroisobutylene and 8 g of vinylidene fluoride added. The reaction mixture was shaken overnight (about 20 hours) at ambient temperature, reaching a peak of 69 psi (470 kPa) at 21.1 °C.
  • optical absorbance per micron in units of inverse microns for P(HFIB/VF2/tBA) (0.29/0.29/0.42) versus wavelength lambda ( ⁇ ) in units of nanometers is shown in Figure 6.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 1.57/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.15/micron.
  • the reaction mixture was shaken overnight (about 20 hours) at ambient temperature, reaching a peak of 10 psi (69 kPa) at 22°C.
  • the fluid reaction mixture was evaporated to dryness, put under pump vacuum for a week, and dried for 7 hours in a 65-90°C vacuum oven. This gave 21 g of brittle solid, which was characterized as indicated below.
  • optical absorbance per micron in units of inverse microns for P(HFIB/VAc/tBA) (0.46/0.27/0.27) versus wavelength lambda ( ⁇ ) in units of nanometers is shown in Figure 7.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 2.16/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.03/micron.
  • Component Wt. (gm HFIB/tBA copolymer (0.41/0.59) as described in this example. 0.234
  • a 240 ml stainless steel autoclave was loaded with 15 ml VertrelTM XF and 14 ml of t-butylacrylate (tBA). After chilling to less than -20°C, 20 ml of about 0.16 M DP in VertrelTM XF were added. The autoclave was sealed, chilled, evacuated, and 32 g of hexafluoroisobutylene and 8 g of vinylidene fluoride added. The reaction mixture was shaken overnight (about 20 hours) at ambient temperature, reaching a peak of 74 psi (510 kPa) at 31.7°C. The fluid reaction mixture was evaporated to dryness, put under pump vacuum for 26 hours, and dried for 30 hours in a 75°C vacuum oven. This gave 10 g of glassy solid, which was characterized as indicated below.
  • a 210 ml autoclave was loaded with 15 ml of VertrelTM XF and chilled to less than -20°C.
  • the autoclave was further loaded with 5.7 ml of t-butylmethacrylate and 20 ml of about 0.17 M HFPO DP in VertrelTM XF.
  • the autoclave was sealed, chilled, evacuated, and loaded with 32 g of hexafluoroisobutylene and 8 g of vinylidene fluoride.
  • the reaction mixture was shaken overnight at ambient temperature (about 20 hours) reaching a peak of 61 psi (421 kPa) at 23°C.
  • the fluid reaction mixture was evaporated to dryness and then put under pump vacuum for 1 week giving 7.9 g of product.
  • An elemental analysis sample dried a further 19 hours in a 50°C vacuum oven gave the following results,
  • HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H solvent were spin coated from l,2-bis(l,l,2,2- tetrafluoroethoxy)ethane at spin speeds of 6000 rpm onto CaF 2 substrates to produce copolymer films of 7930 angstroms thicl ⁇ iess. NUN absorbance measurements were then used to determine the optical absorbance per micron. The optical absorbance per micron in units of inverse microns for
  • the solution used for image generation lithographic evaluation was spin coated from 1 ,2-bis( 1 , 1 ,2,2-tetrafluoroethoxy)ethane at a spin speed of 2000 rpm onto CaF2 substrates to produce copolymer films of 1108 angstroms thickness. VUV absorbance measurements were then used to determine the optical absorbance per micron.
  • optical absorbance per micron in units of inverse microns for copolymer film produced from this formulated resist versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 8B in Figure 9.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 5.37/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.83/micron.
  • EXAMPLE 9 Poly(Hexafluoroisobutylene/Vinylidene Fluoride/t-Butylmethacrylate)
  • the optical absorbance per micron in units of inverse microns for P(HFIB/NF2/tBMA) (0.23/0.26/0.51) versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 9 in Figure 10.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 4.40/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.22/micron.
  • HFIB/NF 2 /tBMA copolymer (0.23/0.26/0.51) as described in this example. 0.290
  • Solvent HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H 2.561 6.82 % (wt) solution of triphenylsulfonium nonaflate dissolved in HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H which had been filtered tlirough a 0.45 ⁇ PTFE syringe filter. 0.150 This solution was subjected to the image generation/lithographic evaluation procedure as described in Example 1. A positive image was produced on the wafer with a clearing dose of approximately 4.3 mJ/cm 2 .
  • the solution used for image generation/lithographic evaluation was spin coated from l,2-bis(l,l,2,2-tetrafluoroethoxy)ethane at a spin speed of 6000 rpm onto CaF2 substrates to produce copolymer films of 2284 angstroms thickness. NUV absorbance measurements were then used to determine the optical absorbance per micron.
  • the optical absorbance per micron in units of inverse microns for copolymer film produced from this formulated resist versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 9A in Figure 10.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 5.71 /micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.88/micron.
  • the optical absorbance per micron in units of inverse microns for copolymer film produced from this formulated resist versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 9B in Figure 10.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 6.43/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 1.08/micron.
  • the optical absorbance per micron in units of inverse microns for P(HFIB/tBA) (0.44/0.56) versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 10 in Figure 11.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 3.74/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.12/micron.
  • HFIB/tBA copolymer (0.44/0.56) as described in this example. 0.290
  • Solvent 65/35 (wt.) HCF 2 CF 2 OCH 2 CH2 ⁇ CF 2 CF 2 H/ 2.561 /2-heptanone 6.82 % (wt) solution of triphenylsulfonium triflate dissolved in HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H which had been filtered tlirough a 0.45 ⁇ PTFE syringe filter. 0.150 This solution was subjected to the image generation/lithographic evaluation procedure as described in Example 1. A positive image was produced on the wafer with a clearing dose of approximately 4.3 mJ/cm 2 .
  • the solution used for image generation lithographic evaluation was spin coated at a spin speed of 6000 rpm onto CaF2 substrates to produce copolymer films of 1160 angstroms thickness. VUV absorbance measurements were then used to determine the optical absorbance per micron.
  • optical absorbance per micron in units of inverse microns for copolymer film produced from this formulated resist versus wavelength lambda ( ⁇ ) in units of nanometers is shown as spectrum 10B in Figure 11.
  • the optical absorbance per micron at 157 nm determined from the copolymer film is 5.43/micron.
  • the optical absorbance per micron at 193 nm determined from the copolymer film is 0.81 /micron.
  • HCF 2 CF 2 OCH 2 CH 2 OCF 2 CF 2 H is significantly better as a spreading solvent on silicon in relation to standard solvents (e.g., 2-heptanone). Solutions are made by dissolving 0.1 g of P(HFIB/VF2/tBMA) (0.23/0.26/0.51) from Example 9 in 1 gram of 2-heptanone and 0.1 g of P(HFIB/NF2/tBMA) (0.23/0.26/0.51) from Example 9 in 1 gram of HCF 2 CF 2 OCH2CH 2 OCF 2 CF 2 H. Both solutions are spotted on silicon wafers and allowed to air dry.
  • standard solvents e.g., 2-heptanone

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Abstract

Cette invention, qui a trait à des copolymères contenant de la fluoro-oléfine/groupe acide ou un groupe acide protégé pour des compositions de photorésines, concerne également des procédé de microlithographie utilisant ces compositions. Ces compositions copolymères contiennent, (1), au moins une fluoro-oléfine, de préférence de l'hexafluoroisobutylène et, (2), un groupe acide ou un groupe acide protégé (par exemple, un ester t-alkyle ou un ester t-butyle), ces substances conférant ensemble une transparence élevée aux ultraviolets ainsi qu'une capacité de développement en milieux basiques à ces compositions. Celles-ci font montre d'une transparence élevée aux ultraviolets notamment à de courtes longueurs d'ondes, par exemple, d'une valeur de 157 nm et de 193 nm, ce qui les rend des plus utiles en matière de lithographie à ces valeurs d'ondes courtes.
PCT/US2001/014532 2000-05-05 2001-05-04 Copolymères pour photorésines et procédés afférents WO2001085811A2 (fr)

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DE60116484T DE60116484T2 (de) 2000-05-05 2001-05-04 Copolymere für photoresistzusammensetzungen und verfahren zur herstellung
AU2001261205A AU2001261205A1 (en) 2000-05-05 2001-05-04 Copolymers for photoresists and processes therefor
JP2001582408A JP2003532765A (ja) 2000-05-05 2001-05-04 フォトレジスト用コポリマーおよびそのための方法
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US7408011B2 (en) * 2002-08-09 2008-08-05 E.I. Du Pont De Nemours And Company Photoresists, fluoropolymers and processes for 157 nm microlithography
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JP2003532765A (ja) 2003-11-05
DE60116484D1 (de) 2006-03-30
AU2001261205A1 (en) 2001-11-20
US20030215735A1 (en) 2003-11-20
WO2001085811A3 (fr) 2002-06-27
DE60116484T2 (de) 2006-08-24
US6872503B2 (en) 2005-03-29
EP1278786A2 (fr) 2003-01-29

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